ci: drop support for guest kernel 4.14

Remove support for generating kernel 4.14 and tests.

Signed-off-by: Pablo Barbáchano <[email protected]>

Author: pb8o

CHANGELOG.md

@@ -16,6 +16,11 @@ and this project adheres to
 
 ### Removed
 
+- [#4804](https://github.com/firecracker-microvm/firecracker/pull/4804): Drop
+  Support for guest kernel 4.14. Linux 4.14 reached end-of-life in
+  [January 2024](https://lore.kernel.org/lkml/2024011046-ecology-tiptoeing-ce50@gregkh/)
+  The minimum supported guest kernel now is 5.10.
+
 ### Fixed
 
 - [#4796](https://github.com/firecracker-microvm/firecracker/pull/4796): Fixed

README.md

@@ -132,9 +132,9 @@ We test all combinations of:
 
 | Instance  | Host OS & Kernel  | Guest Rootfs | Guest Kernel |
 | :-------- | :---------------- | :----------- | :----------- |
-| c5n.metal | al2    linux_5.10 | ubuntu 22.04 | linux_4.14   |
-| m5n.metal | al2023 linux_6.1  |              | linux_5.10   |
-| m6i.metal |                   |              | linux_6.1    |
+| c5n.metal | al2    linux_5.10 | ubuntu 22.04 | linux_5.10   |
+| m5n.metal | al2023 linux_6.1  |              | linux_6.1    |
+| m6i.metal |                   |              |              |
 | m6a.metal |                   |              |              |
 | m6g.metal |                   |              |              |
 | m7g.metal |                   |              |              |

docs/snapshotting/snapshot-support.md

@@ -661,11 +661,5 @@ m6i won't work on an m6g instance.
 
 | *CPU family* | *taken on host kernel* | *restored on host kernel* | *working?* |
 | ------------ | ---------------------- | ------------------------- | ---------- |
-| **all**      | 5.10                   | 6.1                       | Y          |
-| **all**      | 6.1                    | 5.10                      | Y          |
-
-What doesn't work:
-
-- Graviton 4.14 \<-> 5.10 does not restore due to register incompatibility.
-- Intel 5.10 -> 4.14 does not restore because unresponsive net devices
-- AMD m6a 5.10 -> 4.14 does not restore due to mismatch in MSRs
+| **x86_64**   | 5.10                   | 6.1                       | Y          |
+| **x86_64**   | 6.1                    | 5.10                      | N          |